High speed high current switch mechanism



June 11, 1957 v v. J; CATALANO ETAL I HIGH SPEED HIGH CURRENT SWITCH MECHANISM Filed on. 21. 1954 2 Sheets-Sheet l Fig.2.

Inventors- \licfio-r-- J. Catalano,

Cha les' H. T'tus,

4 Thei Attorney.

June 11, 1957 v. J. CATALANO r L 2,795,676

HIGH SPEED HIGH CURRENT SWITCH MECHANISM Filed Oct. 21. 1954 2 Sheets-Sheet 2 I A Inventors v Victor J. Catalano,

Thei Attorney.

United States Patent HIGH SPEED HIGH CURRENT SWITCH MECHANISM Victor J. Catalano, Drexel Hill, and Charles H. Titus, Havertown, Pa., assignors to General Electric Company, a corporation of New York Application October 21, 1954, Serial No. 463,782

9 Claims. (Cl. 200-155) This invention relates to high speed high current electric switch mechanisms, and more particularly to a friction latched rotary type of switch mechanism which operates with exceptionally high speed to close electric contacts adapted to conduct high values of electric current.

In electrical apparatus it is usually highly desirable to operate suitable protective means as rapidly as possible in response to abnormal system conditions. This is particularly true in mechanical rectifier equipments where an abnormal condition of current, such as an arc back, can seriously damage the mechanical rectifying contacts within a very short time. To provide adequate protection, it is desirable to short circuit the mechanical contacts within approximately second following the occurrence of an arc back. A high speed protective switch designed to fulfill this requirement must also be capable of conducting a high value of short circuit current, which may reach a peak value of 100,000 amperes, for a period of at least 0.13 second until a suitable backup circuit breaker can operate to disconnect the mechanical rectifier equipment from the power source.

Accordingly, it is an object of this invention to provide an improved switch mechanism having an exceptionally short time of response for initiating and carrying an extremely high electric current.

A further object of this invention is to provide for a rotary type protective switch friction latching means including a normally energized electroresponsive device which when deenergized will immediately release a rotatable switch member for extremely rapid switch controlling operation.

A still further object of this invention is to provide for a high current circuit a rotary type protective switch mechanism having cooperating movable and stationary switch contacts capable of rapid closure with negligible contact bounce and current arcing.

Another object of this invention is to provide means for conveniently and simultaneously resetting six separate switch contacts and a pair of latching means for a friction latched rotary type protective switch mechanism.

In carrying out our invention in one form, two independently operated contact protective switch mechanisms are provided, each mechanism having a rotatable disclike switch member with three peripheral, spaced apart contact blades. Three stationary switch members are disposed in cooperating relationship with the three contact blades, and the rotatable switch member is strongly biased to a closed position wherein each associated contact blade and stationary switch member are in engagement. Thus a total of six circuits are available for protecting a mechanical rectifier having six mechanical contacts. Each rotatable switch member is held in an open position against its bias by a friction latching means including interleaved sets of cooperating rotatable and fixed resilient friction plates. A force supplied by a strong spring acts through a magnetically held armature and a rigid clamping lever to clamp the interleaved plates to- 2,795,576 Patented June 11, 1957 gether thereby binding the rotatable plates between cooperating fixed plates and preventing the switch member from rotating in accordance with its bias. To release the switch member for rapid circuit making operation, the armature is deenergized, thereby uncoupling the force transmitting linkage and quickly releasing the clamping pressure from the interleaved plates.

Each stationary switch member comprises a plurality of parallel pairs of yieldable contact fingers which are disposed in parallel spaced relation to provide contact surfaces spaced apart in opposing juxtaposition thereby forming a plurality of contact gaps. Upon closing movement of the rotatable switch member, each contact blade arcuately enters the contact gaps of the associated stationary switch member with great speed for sequential engagement with the opposing contact surfaces. Firm contact pressure is maintained both by physical pressure of the yieldable contact fingers and by magnetic force of the short circuit current following parallel unidirectional paths through the contact fingers, and accordingly an extremely high value of current can be made and conducted.

To simultaneously reset both the friction latching means and the rotatable switch member of both protective switch mechanisms after short circuiting operation, a resetting camming arrangement mounted on a single centrally located resetting shaft is provided.

Our invention will be better understood and further objects and advantages will be apparent from the following description taken in conjunction with the accompanying drawings in which Fig. 1 is a side elevational view of a pair of contact protective switch mechanisms embodying our invention, the near side of one switch mechanism being partially cut away to better show certain inner portions thereof; Fig. 2 is a plan view of the switch mechanisms also partially cut away; Fig. 3 is an elevational view of a stationary switch member of a protective switch mechanism, and a cooperating contact blade is shown in alternate open and closed positions; Fig. 4 is a plan view of the stationary switch member and contact blade taken along section line 4-4 of Fig. 3; Fig. 5 is a sectional view of the central portion of a protective switch mechanism taken through the centerline of the operating shaft and showing the operating shaft in full; Fig. 6 is a plan view of the cooperating rotatable and fixed friction plates showing the rotatable plates in alternate open and closed positions; Fig. 7 is a sectional view of the central portion of a switch mechanism taken along section line 7-7 of Fig. 5 with the operating shaft shown in full; and Fig. 8 is a schematic diagram of the electrical connections between a position switch associated with the resetting means of the switch mechanisms and remagnetizing windings of the magnetic latch.

Referring now to Figs. 1 and 2, a base member 11 provides a common support for a pair of contact protective switch mechanisms 12 and 13. Both protective switch mechanisms 12 and 13 are identically constructed and are disposed in opposition on base member 11 to provide a total of six separate pairs of circuit making contacts. The two protective switch mechanisms are independently operated but share a common resetting means. For convenience in the following description, only one reference character will be used to identify a part which is common to both mechanisms 12 and 13.

Each protective switch mechanism is mounted on a frame structure comprising a rectangular supporting plate 14 connected to and spaced apart from one end of the base member 11 by four rigid column members 15. Each column member 15 has a square cross section and is fastened to plate 14 by a bolt 16. On the top surface of each supporting plate 14, as viewed in Fig. 2, there are three insulating blocks 17. These blocks face inwardly from near the outer edges of the plates 14 and are spaced radially at 120 degree intervals, as is clearly shown in Fig. 2. A hexagonal plat-e 18 having a circular portion removed from its center extends over the top of all three insulating blocks 17, and two mounting bolts 19 per block firmly clamp the cover plate 18 and the blocks 17 to supporting plate 14 of the frame structure. A vertically disposed current conducting channel 20 is mounted on the rear surface of each insulating block 17 by a pair of bolts 21. Heavy electric cables having very high current carrying capacity, as represented in Fig. l by reference character 22, are connected to the channels 20 from a remote mechanical rectifier being protected by the contact protective switch.

A recess in each insulating block 17 houses a stationary switch member 23a, as can be seen in Figs. 3 and 4. Stationary switch member 23;: comprises a pair of spaced apart current conducting support arms 23 welded to the channel 20 and extending inwardly in parallel spaced apart relation through insulating block 17. Two current conducting pins 24, one above the other, extend laterally through both arms 23 to provide supporting means for four laterally disposed switch elements located between the arms. Each switch element comprises a pair of parallel, spaced apart, opposing contact fingers 25, each finger of the pair having one end pivotally connected to a different pin 24. The switch elements are separated laterally by suitable insulating spacers 26 located on pins 24 between each contact finger. The other end of each contact finger 25 extends beyond the face of the insulating block 17 and terminates with a convex contact surface 27 formed from suitable contact material. The contact surfaces 27 of the two fingers forming a switch element oppose each other to define a contact gap for admission of a tip 28 of a cooperating movable contact blade 29.

The minimum distance between opposing contact surfaces 27, which is determined by a spacer bar 30 extending laterally between support arms 23 and disposed in the space between each pair of fingers 25, is smaller than the full thickness of tip 28.

Each pair of fingers 25 is strongly biased by a pair of leaf springs 31 to a position wherein spacer bar 30 is engaged and minimum contact gap is maintained. One end of each leaf spring 31 is fixedly connected to one edge of both support arms 23 by :a pair of screws 32 in combination with a plate 33, while the other end is tapered and split to form four fingers each of which applies bias force to one contact finger 25 of each switch element. A thin strip of low electrical resistance current conducting material 34 having the same configuration as leaf spring 31 is inserted under the leaf spring to provide a path for current flow between the contact fingers 25 and the support arm 23. This protects the leaf spring 31 from any abnormal effects that might otherwise result from conduction of a high value of current through the spring itself. However, most of the large total short circuit current flowing upon switch operation will follow parallel paths in the same direction through the contact fingers 25 to the pair of pins 24, and through pins 24 to the pair of support arms 23 connected to channel 20. A pair of tension springs 35 is provided to supply a force tending to pull the pins 24 into good electrical contact relation with both the contact fingers 25 and the arms 23, thus insuring that good contact is maintained under all operating conditions.

The supporting plate 14 of each frame structure has a circular portion removed from its center. A housing member 36 is bolted by five flat head screws 36a to the bottom surface of supporting plate 14 immediately below this circular aperture. As can be seen in Fig. 5, a vertically disposed rotatable, cylindrical operating shaft 37 extends through the aperture and into a recess in housing 36. The lower portion of the shaft 37 extends into a cooperating hole in the bottom wall of housing 36, and four lugs 33 formed at degree intervals on shaft 37 provide stop means to determine the vertical position of shaft 37 with respect to housing 36 and plate 14. a collar 39 is welded to supporting plate 14 inside the aperture, and a sleeve bushing 40 is inserted therein to provide bearing surface for cylindrical shaft 37 and to secure proper vertical alignment thereof.

A constricted portion 41 having a square cross section is formed in shaft 37 near its upper end. A thin disclike switch member 42 having a cooperating square aperture in its center is placed over this portion of shaft 37. Shaft 37 terminates at its upper end in a threaded portion 43, and a cooperating terminal sleeve 44 can be screwed thereon. Thus the switch member 42 is locked in place on shaft 37 between the terminal sleeve 44 and a shoulder formed by the cylindrical portion of shaft 37. Terminal sleeve 44 is adapted to receive a heavy, flexible electric cable 45 having very high current carrying capacity and connected to the remote mechanical rectifier being protected by the shorting switch.

Three radially disposed contact blades 29 each terminated by a contact tip 23 are spaced at degree intervals on the periphery of each disc-like member 42, as can be seen in Fig. 2. The contact tips 28 are formed of suitable current conducting material. Each tip 28 has a thin body portion defined by flat surfaces parallel to the disc-like switch member 42 and a wedge shaped forward portion terminating in a knife like edge 45. The blade 29 and tip 23 are disposed on switch member 42 in a manner whereby edge 46 forms an oblique angle with any line drawn between the edge 46 and the center of rotation of shaft 37. Thus one end of edge 46 is a greater radial distance from the center of rotation and defines a greater arc than the other end upon rotation of switch member 42.

Switch member 42 is disposed for reciprocating movement between an extreme counterclockwise or open position, as viewed in Fig. 2, wherein each contact blade 29 is physically separated and electrically isolated from a cooperating stationary switch member, and an extreme clockwise or closed position wherein each contact blade 29 is electrically engaged with the cooperating stationary switch member. Each insulating block 17 is positioned on supporting plate 14 in a manner whereby each stationary switch member 23a is disposed in divergent angular relationship with the cooperating contact blade 29. Whenever the switch member 42 is in its open position, a line drawn laterally through the centers of the contact gaps of each switch element of the stationary switch member 23a will be parallel to edge 46 of the cooperating movable contact blade 29. In Fig. 4 the contact tip 28 is shown by a solid line to indicate its position when switch'rnember 42 is in the above mentioned open position, while a broken line indicates the position of contact tip 28 after the switch member 42 is rotated to its closed position. Figs. 1 and 2 illustrate the contact protective switch with switch member 42 in its open position.

The closed position of the rotatable switch member 42 is determined by a stop member comprising a tubular section 47 loosely surrounding collar 39 and having an arm 48 connected thereto. The tubular section 47 has three coaxial projections 49 disposed at 120 degree intervals and extending into the space between contact blades 29, as shown in Figs. 1, 2 and 5. The arm 48 extends through the space between two insulating blocks 17 and is disposed between opposing adjusting screws 50. Each adjusting screw 50 is threaded through a bracket 51 which is welded to the top of supporting plate 14. As can be seen in Figs. 1 and 2, arm 48, and therefore tubular portion 47, is held firmly between screws 50, and its position can be adjusted by loosening one screw and tightening the other. Thus the position of the three projections 49 can be adjusted. When the switch member 42 is rotated clockwise, the leading edge of each contact blade 29 will strike and be stopped by a projection 49 to determine the extreme clockwise or closed position of the switch member.

Each reciprocally rotatable switch member 42 is biased to its closed position by three powerful compression springs 52. As shown in Fig. 2, each spring 52 is seated in a cooperating recess located in an insulating block 17. A screw 53 is provided in each block 17 to precompress spring 52 and therefore increase the force exerted by the spring. Each spring 52 engages the trailing edge of a different contact blade 29 and applies a strong bias force at this point in a tangential direction tending to rotate the switch member in a clockwise direction.

To hold switch member 42 in its open position against the force of the bias springs 52, we provide a friction clamping means comprising cooperating pairs of interleaved movable and fixed friction plates 54 and 56 respectively. As shown in Figs. 6 and 7, three parallel generally rectangular shaped rotatable friction plates 54 are keyed by lugs 38 to shaft 37 and are disposed in spaced apart relation by suitable washers 55. These plates extend from opposite sides of shaft 37 in the recess in housing 36 and lie in planes substantially perpendicular to the axis of the shaft. The ends of plates 54 are yieldable in a direction normal to their planes and have smooth friction clamping surfaces. A set of 4 cooperating spaced apart fixed friction plates 56 is located at each end of the rotatable plates 54. The outer end of each friction plate 56 is fixed to supporting plate 14 by a pair of bolts 57. As shown in Fig. 7, the upper plate 56 lies firmly against the lower surface of supporting plate 14 in flatw-ise engaging relation, and three suitable spacers 53 are used for maintaining a gap between adjacent friction plates. The inner end of each plate 56 is resilient and has smooth friction clamping surfaces. The ends of the rotatable friction plates 54 are interleaved between adjacent fixed friction plates 56 with corresponding friction clamping surfaces overlapping.

Clamping pressure is applied to the friction clamping means by a pair of rocking type clamping levers 59, shown in Figs. 5 and 7. Each lever 59 is generally L-shaped and includes at one end a rounded bearing portion engageable with the bottom friction clamping surface of the lowest friction plate 56. Each lever 59 is coupled at its other end by means of a pin 59a to a common armature member 60, and intermediate its ends lever 59 is pivotally connected to housing 36 by a threaded pin 61. Whenever rotatable switch member 42 is in its open position, the rotatable friction plates 54 will be directly in line with the fixed friction plates 56, as shown by the solid line in Fig. 6. By means of the clamping levers 59, clamping pressure is applied in a direction normal to the planes of the clamping surfaces thereby clamping the interleaved plates 54 and 56 between levers 59 and supporting plate 14, and firm engagement between all cooperating clainping surfaces is established. The resulting frictional resistance is sufiicient to hold the shaft 37 against .the torque set up by bias springs 52 tending to rotate the shaft clockwise. Upon release of the clamping pressure, the frictional resistance between clamping surfaces will become inadequate to hold shaft 37 against the strong bias force, and the rotatable friction plates 54 will slide across the cooperating fixed friction plates 56 while switch member 42 rotates clockwise to its closed position. The new position of the rotatable friction plates 54 is shown in Fig. 6 by a dot-dash line.

The clamping pressure applied by clamping lever 59 is supplied from a powerful compression spring 62 acting through a linkage including a frame member 63 and armature member 60 of a flux shifting permanent magnetic type latch. As can be seen in Fig. 1, frame member 63 is pivotally connected to an adjustable support. The support comprises an insulating member 64 spanning the end pair of column members 15 and bolted thereto through vertically slotted holes by a pair of bolts '65, and a bracket 66 connected to member 64 by a strap 67 and two bolts 68. Frame member 63 is pivotally connected to bracket 66"by a horizontally disposed pin 69. A pair of adjusting bolts 70 extend vertically through plate 14 and are threaded into member 64 to provide a means for initially adjusting the vertical position of the support and consequently the vertical position of the electromagnet. A look nut 71 securely binds each bolt 70 after the desired adjustment has been made.

An elongated projection of frame member 63 extends toward the mid-portion of base member 11 and terminates with a roller 72 which revolves in a plane substantially perpendicular to this projection. As the frame member 63 pivots on pin 69, roller 72 will move up and down in a vertically slotted guide bracket 73 which is fastened to base member 11 by a screw 74. The projection of frame member 63 is adapted to receive one end or" compression spring 62.

Spring 62 provides a force tending to rotate frame 63 about pivot 69. As viewed in Fig. l, for protective switch mechanism 12 the direction of pivotal movement under the influence of spring 62 is clockwise, while for switch mechanism 13 the direction is counterclockwise. In both cases pivotal movement is limited by a stop 75 which projects from base 11 in cooperating relationship with the extended portion of frame member 63. The initial deflection of spring 62, and thus its force, can be adjusted by turning a bolt 76 into or out of housing member 36. Spring 62 is designed to have a very low spring gradient thereby minimizing the effect of mechanical variations on the force supplied by this spring.

Whenever armature member 60 is attracted to or seated on frame member 63, the force of spring 62 will be transmitted through the magnetic latch to clamping levers 59, and the friction clamping means will hold shaft 37 against its bias. The clamping pressure applied actually is greater than the force available at spring 62 due to a force amplifying linkage arrangement. The moment arm of the force at pin 59a, i. e., the distance between pivot 69 and the line of force through pin 59a, is less than the moment arm of the spring force, i. e., the distance from spring 62 to pivot 69; therefore the force at pin 59a is correspondingly greater than the spring force. Similarly, the clamping pressure is greater than the force at pin 59a by the reciprocal of the ratio of moment arms of these two forces with respect to pivot 61.

To hold armature member 60 in an attracted or seated position on frame member 63, the magnetic latch is provided with a permanent magnet. The magnet establishes a magnetic field having sufficient strength to hold armature 60. A remagnetizing winding 80 is provided to remagnetize or strengthen the permanent magnet whenever winding 8!) is energized. To release the armature, and thus remove the clamping pressure, the frame member 63 is provided with a special flux shifting pole face construction and an actuating coil 81. This coil 81 when energized will instantly divert or shift the magnetic flux from its normal path through armature 60. The armature is thereby de-energized and will be released from its force transmitting attracted position.

The pair of clamping levers 59 together with pins 59a and 61 are designed to have maximum rigidity and minimum elasticity. The pins 59a and 61 are disposed in a manner to be stressed only in shear with substantially no bending. As a result,the lever system between armature 60 and the friction clamping means is extremely rigid and nonresilient, and the bearing portion of lever 59 will move away from the friction plates substantially in stantaneously with movement of armature member 60 away from frame member 63.

A single resetting mechanism is provided to reset simultaneously both protective switch mechanisms 12 and 13 after operation. As shown in Figs. land 2, a vertically, disposed rotatable resetting shaft '82 is centrally located on base member 11. A bevel gear 83 is pinned to shaft 82 for engagement by Suitable driving means, not shown, such as. a motor driven cooperating gear system, to rotate shaft 82 in a clockwise direction. A camming disc 84 is connected to the lower end of shaft 84 for rotation therewith. Roller 72 rides over this disc and is lifted by two diametrically opposed raised portions of the disc thereby lifting frame member 63 to a reset position against the force of spring 62.

Immediately above supporting plate 14, resetting shaft 82 carries a wing-shaped cam member 85 which extends from opposite sides of shaft 82 in cooperating relationship With a resetting arm 86 of each shorting switch mechanism. Resetting arm 86 extends between adjacent insulating blocks 17 and pivotally connects to the operating shaft 37. Three elongated slots 87 radially spaced at 120 degree intervals in the pivotally connected portion of arm 86 are disposed in cooperating relation with three short lugs 88 located on shaft 37. Arm 86 is held in a normal operating position, illustrated in Fig. 2, by a bias spring 89. In this position, lugs 88 can freely travel in slots 87 as shaft 37 rotates to carry reciprocably movable switch member 42 from its open to its closed position. To reset the protective switch, i. e., to return switch member 42 to its open position after operation, resetting shaft 82 is rotated to turn cam'member 85. Movement of cam member 85 tilts resetting arm 86, and the lugs 88, which are now engaged with the trailing edge of slots 87, will be compelled by arm 86 to rotate operating shaft 37 against its bias.

It can be seen that rotation of resetting shaft 82 through one quarter of a full revolution will reset both the frame member 63 and the operating shaft 37 of both protective switch mechanisms 12 and 13, and that an additional 90 degree movement will return the resetting mechanism to its normal position in readiness for another resetting cycle.

An indicating switch 90 is associated with each protective switch mechanism. This switch, which operates in response to movement of rotatable switch member 42, provides an indication of the position of switch member 42 and may be used, for example, in a manner to prevent operation of the resetting means until after the switch mechanism has operated. As can be seen in Fig. 2, indicating switch 90 is secured to a bracket 91 which is fastened to supporting plate 14 by a pair of screws 92. .An actuating lever 93 pivotally connected to plate 14 operates switch 90 in response to movement of the rotatable switch member 42. This lever 93 is held by spring pressure of a switch operating push button 94 against the trailing edge of a contact blade 29, and upon closing movement of switch member 42 the lever tilts to release the push button for switch controlling operation. Electrical connections to switch 90 have not been shown.

Four positionswitches 95 are associated with the resetting mechanism to perform circuit controlling functions dependent on the position of the resetting shaft 82. These switches which are similar to indicating switch 90, are mounted on a bracket 96 which is secured to an intermediate plate 97 between the two supporting plates 14. The upper three switches 95, as viewed in Fig. l, are operated in unison by a single actuating lever 98 pivotally connected to plate 97 and may be used, if desired, to control the remote driving means, not shown. The lowest switch 95 is operated by an actuating lever 99 also pivotally connected to plate 97, and this switch is connected to remagnetizing windings 80, as shown in Fig. 8, thereby to control the energization of these windings during resetting. The positions of the actuating levers 98 and are controlled by two cooperating discs, 100 and 101 respectively, suitably connected to resetting shaft 82 for rotation therewith. Each disc has diametri- 8 'cally opposed slots in its periphery, the slots of disc 100 being displaced degrees from those of disc 101. As a disc rotates, the cooperating actuating lever will move into a slot under the urging of a position switch operating push button 102' thereby releasing the push button for switch controlling operation.

From the foregoing detailed description of the structure of our contact protective switch mechanisms, the mode of operation may now be readily followed. Normally the reciprocably rotatable switch members 42 are retained in their open position by the friction clamping means. The actuating coils 81 of both switch mechanisms may be connected in series circuit relation for simultaneous energization immediately in response to a predetermined abnormal change of conditions at the remote mechanical rectifier being protected. Energization of the actuating coil 81 of the magnetic latch will instantly shift the flux of the permanent magnet from its normal path through armature 60, thus releasing the armature from its attracted or force transmitting position. This uncouplcs the linkage which transmits force from compression spring 62 to clamping lever 59 thereby disabling spring 62.

The removal of force from armature 60 is instantly reflected through the pair of rigid clamping levers 59 by removal of clamping pressure from the interleaved friction plates 54 and 56. Clamping levers 59 will tilt on their pins 61 as the resilient ends of the cooperating friction plates respond to the release of clamping pressure. The frictional resistance between cooperating clamping surfaces is diminished as the rounded bearing portion of each lever 59 retreats from its fully clamped position; and, after practically infinitesimal movement of the levers 59, the strong biasing force of springs 52 acting upon rotatable switch member 42 will overcome the resulting weakened frictional resistance to rotate shaft 37 clockwise.

Because the components of operating shaft 37 are small and lightweight, the total mass moved upon rotation of this shaft is relatively small and its inertia is correspondingly low. Consequently, shaft 37 will rotate clockwise with great speed.

Switch member 42 rotates with shaft 37 to carry each contact blade 29 into engagement with an associated stationary switch member. The contact tip 28 of contact blade 29 arcuately enters the contact gaps formed by opposing contact surfaces 27 of the four parallel switch elements comprising a stationary switch member 23a, and tip 28 continues moving therein until clockwise rotation of shaft 37 is stopped by the engagement of the leading edge of each contact blade with a projection 49 of the stop member. As the contact tip enters the gaps, the wedge shaped forward portion of the contact tip forces each pair of contact fingers 25 apart against the bias of leaf springs 31. In the extreme clockwise or closed position of switch member 42, firm engagement between all contact surfaces 27 and the flat body portion of the contact tip 28 is maintained by the force of the leaf springs 31. In Figs. 3 and 4 the positions of a contact tip 28 for the open and closed positions of switch member 42 are shown by solid and broken lines respectively.

To minimize the reactive effect on switch member 42 as contact tip 28 engages and forces apart the c'bntact fingers 25, we have designed our switch mechanism so that contact tip 28 is disposed in divergent angular relation with respect to the contact fingers 25. Therefore, as the contact tip 28 arcuately enters the contact gaps it will engage the switch elements in sequence. As the pairs of contact fingers 25 are sequentially spread apart, contact tip 28 encounters only a relatively small reactive force at each instant, and the undesirable condition of contact bounce is prevented.

Upon engagement of contact tip and contact surfaces, an extremely high value of current may begin to flow. This current will follow generally a path having very little inductance comprising a conductor 22, channel 20,

a pair of supporting arms 23, a pair of pins 24, 8 contact fingers 25, contact surfaces 27, contact tip 28, contact blade 29, and switch member 42. Switch member 42 provides a short circuit path for the interchange of currents between each of the three conductors 22 and the conductor 45 connected to each shorting switch mechanism. The low inductance of this short circuit permits a high value of current to How instantly thereby providing optimum protection for the mechanical contacts. The high current conducted by each pair of contact fingers establishes a magnetic field which exerts a force on the contact fingers tending to press them together thereby aiding leaf springs 31 and increasing contact pressure.

The contact protective switch mechanisms will be required to conduct a high value of current, which may reach a peak value of 100,000 amperes, for at least 0.13 second until a suitable back-up circuit breaker responds to the short circuit condition to interrupt the circuit.

The overall operating time for the illustrated embodiment of our high speed high current switch mechanism has been found to be approximately second, including 33 second to release armature 60 after energization of the actuating coil 81.

After operation of the protective switch mechanisms 12 and 13 followed by the opening of the back-up circuit breaker, the switch mechanisms may be jointly reset by rotating resetting shaft 82 through 180 degrees. Frame member '63, which rests on stop 75 as shown for switch mechanism 13 by the broken line in Fig. l, is pivotally raised against the force of compression spring 62 as camming disc 84 rides. under roller 72. Simultaneously, resetting arm 86 is tilted by cam member 85 to rotate operating shaft 37 counterclockwise against the force of bias springs 52. After resetting shaft 82 has been rotated 90 degrees, rotatable switch member 42 is in its extreme counterclockwise or open position, and frame member 63 has been raised into cooperating relationship with armature member 60. At this instant, due to the operation of the lowest position switch 95 by actuating lever 99, the remagnetizing coil 80 of the magnetic latch is energized to remagnetize the permanent magnet which then is able to hold armature 60 in its attracted position. This action makes whole the force transmitting linkage between spring 62 and clamping lever 59, and clamping pressure will be exerted on the interleaved friction plates to hold shaft 37 and switch member 42 in the open position. Rotation of resetting shaft 82 will continue for another 90 degrees at which point the driving means and shaft 82 stop rotating. Stoppage of the driving means may be controlled by operation of the upper three position switches 95. Both cam member 85 and camming disc 84 are now in a position to permit subsequent operation of the protective switch mechanisms.

While we have shown and described a preferred form of our invention by way of illustration, many modifications will occur to those skilled in the art. We therefore contemplate by the appended claims to cover all such modifications as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A high speed switch mechanism comprising a lightweight reciprocably rotatable disc-like switch member strongly biased to a first circuit controlling position, friction clamping means disposed to hold said switch member against its bias in a second circuit controlling position, a rigid clamping lever pivoted at a fixed point and disposed in pressure applying relationship with said friction clamping means, a clamping force supplying means, a normally energized electroresponsive device interconnecting said clamping lever and said clamping force supplying means in force transmitting relation, and means for deenergizing said electroresponsive device to disconnect said lever and force supplying means thereby substantially instantaneously to remove pressure from said friction clamping means and to release said switch member for rapid rotary switch actuating movement.

2. A high speed switch mechanism comprising a lightweight movable switch member strongly biased to a first circuit controlling position, friction clamping means disposed to hold said movable switch member against its bias in a second circuit controlling position, an elongated rigid rocking lever arm pivoted at a fixed point and disposed in pressure applying relationship with said friction clamping means, clamping force supplying means, a force transmitting linkage including a magnetic latch having a movable frame member connected to said force applying means and a cooperating armature coupled to said lever arm, said linkage disposed to transmit clamping force to said lever arm whenever said magnetic latch is energized, and means for deenergizing said magnetic latch to uncouple said force transmitting linkage thereby instantly releasing said lever arm and removing pressure from said friction clamping means to release said switch member for rapid switch actuating movement in accordance with its bias.

3. A high speed switch mechanism comprising, a lightweight movable switch member strongly biased to a first circuit controlling position, friction clamping means disposed to hold said movable switch member against its bias in a second circuit controlling position, an elongated pivotally mounted rigid lever arm disposed to apply clamping force to said clamping means, spring means for supplying a force, a force amplifying and transmitting linkage including a releasable magnetic coupling having a pivotally mounted frame member connected to said spring means and a cooperating normally energized armature coupled to said lever arm, said magnetic coupling disposed to transmit to said lever arm an amplified force wit-h despect to the force supplied by said spring means, said lever arm disposed to apply to said clamping means an amplified clamping force with respect to the force transmitted by said magnetic coupling, and means for deenergizing said armature to uncouple said magnetic coupling thereby substantially instantaneously to remove said clamping force and to release said switch member for rapid switch actuating movement.

4. A high speed switch mechanism comprising, a lightweight disc-like switch member mounted on a rotatable shaft strongly biased to a first angular position, friction clamping means disposed to hold said shaft against its bias in a second angular position, spring means for supplying a force, a force transmitting linkage including a releasable magnetic coupling having an elongated frame member pivotally mounted at one end and connected to said spring means at its other end and having a cooperating normally energized armature disposed intermediate the ends of said frame member, an elongated rigid lever arm pivotally mounted intermediate its ends at a fixed point and having one end coupled to said armature and its other end disposed to apply clamping pressure to said clamping means in response to force transmitted by said linkage to said lever arm from said spring means, and means for deenergizing said armature to release said magnetic coupling thereby to instantly remove said clamping pressure and to release said shaft for rapid rotary movement in accordance with its bias.

5. A high current electric switch mechanism comprising a plurality of parallel pairs of yieldable contact fingers, the fingers of each of said pairs disposed in opposing relationship and having adjacent spaced apart contact surfaces defining a contact gap, spring means disposed to bias each of said fingers toward. its associated opposing finger, and a reciprocally notatable switch member having a wedge-like peripheral contact blade disposed arcuately to enter said contact gaps thereby sequentially to engage adjacent contact surfaces and to spread apart each pair of contact fingers against the bias of said spring means upon switch actuating movement of said switch member.

6. In a high current electric switch mechanism, a plurality of switch elements disposed in laterally spaced apart relation, each said switch element comprising a pair ,of opposing yieldable contact fingers having adjacent contact surfaces transversely spaced apart to define a contact gap, bias means associated with said contact fingers for maintaining a predetermined minimum distance between said contact surfaces, and a rotatable switch member hav ing a peripherally disposed contact blade movable in a lateral plane arcuately into and out of said contact gaps, said blade comprising a body portion having a thickness greater than said predetermined minimum distance and a generally wedge-shaped forward portion whereby movement of said blade into said contact gap will force said contact fingers apart against their bias to establish good electrical contact between said contact surfaces and said body p01ti011.

7. A high current electric switch mechanism comprising, a plurality of parallel pairs of yieldable contact fingers, the fingers of each said pair disposed in opposing relationship and having adjacent spaced apart contact surfaces defining a contact gap, spring means disposed to bias each said finger toward its associated opposing finger, and a rotatable switch member having a peripheral wedge-like contact blade movable arcuately between a first position wherein said contact blade and fingers are electrically iso lated and a second position wherein said contact blade firmly engages said adjacent contact surfaces of each. said pair of contact fingers, said contact blade disposed in divergent angular relationship with said pairs of contact fingers, whereby said contact blade sequentially engages said pairs of contact fingers during rotary movement of said switch member from said first to said second positions.

8. A protective electric switch mechanism comprising, a lightweight movable switch member strongly biased to a first circuit controlling position, friction clamping means disposed to hold said switch member against its bias in a second circuit controlling position, clamping pressure applying means including a normally energized magnetic latch having a frame member pivotal-1y mounted at a fixed point and a norm-ally attracted cooperating armature coupled to said friction clamping means in pressure applying nelation, means for deenergi'zing said magnetic latch thereby to disable said clamping pressure applying means and to release said switch member for rapid switch actuating movement in accordance with its bias, and resetting means operable to return said rotatable switch member against its bias to said second circuit controlling position and simultaneously to pivot said frame member into attracted relation with said armature.

9. A protective electric switch mechanism comprising, a pair of parallel spaced apart rotatable operating shafts, a pair of switch members each fixedly mounted on different said operating shaft and biased to a first circuit controlling position, a pair of friction clamping means each disposed to hold a different said switch member against its bias in a second circuit controlling position, a pair of clamping pressure applying means each including a magnetic latch having a pivotally mounted fname member strongly biased to a first angular position and a cooperating normally energized armature disposed to hold said frame member against its bias in a second angular position, each said armature coupled to a different said clamping means in pressure applying relation, means for deenergizing said ar-matures to release said frame members for pivotal movement to said first angular position thereby removing clamping pressure from said clamping means and releasing said switch members for rotary movement to said first circuit controlling position, a rotatable resetting shaft disposed parallel to and intermediate said operating shafts, first cainming means fixedly mounted on said resetting shaft and releasably coupled to both said operating shafts to return said switch members from said first to said second circuit controlling positions upon rotation of said resetting shaft, and second camming means fixedly mounted on said resetting shaft and releasably coupled to both said frame members to return said frame members from said first to said second angular positions upon rotation of said resetting shaft.

References Cited in the file of this patent UNITED STATES PATENTS 596,097 Wellman et al. Dec. 28, 1897 1,002,855 Lietzenmayer Sept. 12, 1911 1,978,246 Bauerschmidt Oct. 23, 1934 2,620,901 Stearns Dec. 9, 1952 

